Telescopic tubes



Sept. 9, 1969 H. DEPLANTE TELESCOPIC TUBES Filed July 31. 1967 UnitedStates Patent Oihce 3,466,062 Patented Sept. 9, 1969 Int. c1. F16127704, 27/00, 5/00 U.S. Cl. 285-165 4 Claims ABSTRACT OF THE DISCLOSUREA telescopic tube comprising a first cylinder having with a base inwhich an aperture is formed, a second cylinder disposed coaxially withinthe first cylinder in fixed relationship thereto, and a third coaxialcylinder disposed radially between the first two cylinders to slide in asealed manner through the aperture formed in the base of the firstcylinder, and a piston carried by the third cylinder to slide in asealed manner between said first two cylinders, the third cylinderhaving an orifice in its cylindrical wall. The Volume occupied by afluid in such a telescopic tube varies relatively little or not at allduring deformation.

The present invention relates to a telescopic tube.

A general way of effecting remote control is to employ a hydrauliccircuit. In certain cases, for example in the case of avariable-geometry aircraft of the swing-wing type, part of the circuitis incorporated in a deformable device. Generally speaking, the spacecontaining the hydraulic fluid changes in volume during deformation. Theresult of this is undesired changes in the pressure of the hydraulicfluid, which reduces the precision of control.

The object of the invention is to provide a telescopic tube in which thevolume occupied by the fluid varies relatively little or not at all,during deformation.

The telescopic tube in accordance with the invention comprises a firstcylinder equipped with a base in which there is an aperture, a secondcylinder parallel to the first, located inside it and fixed in relationthereto, and a third cylinder parallel to the first two and situatedbetween them whilst being able to slide in a sealed manner through theaperture formed in the base of said lirst cylinder, said third cylinderbeing provided with a piston which is able to slide in a sealed mannerbetween said first two cylinders, the third cylinder in additioncontaining an orifice in its cylindrical wall.

The following description with reference to the accompanying drawingwill indicate by -way of example how the invention maybe carried intopractice.

In the drawing:

FIGURE la is an elevational view of one extremity of a telescopic tubein accordance with the invention;

FIGURE lb is an elevational section, on the brokenline Ib-Ib of FIGURE2b, through the other extremity of the same telescopic tube;

FIGURE 2a is a section, taken on the line IIa--Ila of FIGURE la, of thefirst extremity of the telescopic tube;

FIGURE 2b is a section, taken on the line IIb-1lb of FIGURE lb, throughthe other extremity of the telescopic tube.

In the drawing, indicates a first cylinder provided with a base 11 inwhich there is an aperture, and 12 indicates a second cylinder parallelto the first cylinder 10, located inside it and fixed in relationthereto. The reference 13 indicates a third cylinder, parallel to thefirst two cylinders 10 and 12 and situated between them. Two seals 14and 15 are disposed in annular throats produced in the cylindricalinternal surface of the base 11 of the first cylinder 10. These sealsenable the third cylinder 13 to slide in a sealed manner through theaperture in the base 11 of the first cylinder 10.

The third cylinder 13 is provided, at that extremity situated betweenthe first cylinder 10 and the second cylinder 12, which an annularpiston 43 capable of sliding in a sealed manner between said twocylinders. The piston 43 possesses two annular seals 44 and 45 disposedin undercuts produced in the cylindrical external surface of the piston,and a seal 46 situated in an undercut produced in the cylindricalinternal surface of the piston. These three seals 46, 44 and 45 ensurethat the piston 43 cooperates in sealing relationship with the firstcylinder 10 and with the second cylinder 12.

The cylindrical wall of the third cylinder 13 is pierced by orifices 16situated in a transverse ring and allowing communication between anannular space 47 formed between the first cylinder 10 and the thirdcylinder 13 and an annular space 48 formed between the second cylinder12 and the third cylinder 13. A collar 17 carried by the third cylinder13 is situated in the neighbourhood of the orifices 16. The periphery ofthis collar is crenellated and fluid therefore fiows past it when thethird cylinder 13 and its piston 43 are displaced. It acts as amechanical stop, in conjunction `with the base 11 of the first cylinder10, to limit the maximum extension of the telescopic tube formed by theabove-described arrangement of cylinders.

If, for example, it is assumed that the third cylinder 13 and its piston43 are being displaced towards the right in relation to the rigidassembly constituted by the first cylinder 10 and the second cylinder12, and if the area of the internal transverse cross section of thethird cylinder 13 is designated S, it will be apparent that the volumeoccupied by the fluid at the right of the second cylinder 12 increasesby a volume equal to the product of the longitudinal displacement of thethird cylinder 13 and the area S. However, at the same time, the volumeoccupied by the fluid in the annular space 47 formed between the firstcylinder 10 and the third cylinder 13, and in the annular space 48formed between the second cylinder 12 and the third cylinder 13,diminishes by a volume equal to the product of the displacement of thecylinder 13 and the sum of the areas of the transverse cross sections S1and S2 of said annular spaces 47 and 48. If S=S1+S2, the total volumeoccupied by the fluid is unchanged. If to the two members of thisequation there is added the area of the transverse cross section of thewall of the third cylinder 13, the new equivalent resulting equation maybe expressed as follows: the cross sections of the third cylinder 13,including its Wall, and of the annular space defined by the firstcylinder 10 and the second cylinder 12 have substantially equal areas.

Generally speaking, there will not be only a longitudinal displacementof the third cylinder 13 in relation to the first cylinder 10 and thesecond cylinder 12. If, for example, the telescopic tube is linking thefuselage to the swing-wing of a variable-geometry aircraft, it isnecessary generally speaking, at one end of the telescopic tube, for therigid part constituted by the first and second cylinders (or for thatmatter at the other end for the rigid part constituted by the thirdcylinder), to be connected to a union which is able to swivel inrelation to the ltube about a geometric axis which can adopt any desiredspatial orientation. This movement is provided by creating a universaljoint between one of these two rigid parts and the union. A joint ofthis sort is illustrated in the drawing for each of -the said two rigidparts.

At the right-hand side of FIGURE 2b, the third cylinder 13 is continuedin the form of a terminal portion 49 of reduced section, containing abore 51. A first union 34, containing a bore 53 communicating with thebore 51, can swivel about the terminal portion 49 and a second union 35,containing a bore 36 communicating with the bore 53, can swivel aboutthe first union 34. Nuts 41, 42 and 5S, washers 50, 52 and 54 and seals37, 38, 39, 40, 56 and S7 serve to fix the components together andprovide sealing.

At the left-hand side of the FIGURE 2a, the second tube 12 terminates inan enlarged cylindrical portion 25 carrying a flange 24 which bearsagainst a shoulder 20 on the first tube 10. An elbow union 18 containinga bore 58 is provided, having two branches 28 and 29 at right-angles toone another, the first of which enters the enlarged portion 2S andpossesses a collar 19 which bears against the ange 24 so that the union18 can swivel about the longitudinal axis of the telescopic tube.Another union 33, containing a bore 23 communicating with the bore 58,can swivel about the arm 29 of the union 18. Nuts 21, 30 and 22 andseals 26, 31 and 32 lock and seal the assembly.

A thrust washer is located between the nut 21 and the collar 19. Thiswasher is of the split type, the split plane being in the plane ofsection of the drawing (FIGURE 2a). Undercuts 60 and 63 are formed inthe periphery of the enlarged cylindrical portion 25 and in theperiphery of -the collar 19. The volume 62 formed between the enlargedportion 25 and the piston 43 communicates with I claim:

1. A telescopic tube comprising a first cylinder having an aperturedbase, a second cylinder disposed inside in the first cylinder in fixedcoaxial relationship thereto, a third cylinder coaxial with said rst twocylinders and disposed radially between them to slide in the axialdirection through the aperture formed in the base of the first cylinder,said third cylinder and said aperture being in sealing relationship, andan annular piston carried by the third cylinder to slide between saidfirst two cylinders, said piston and the walls of said first twocylinders being in sealing relationship, and the Ithird cylinder inaddition having an orifice in its cylindrical wall putting intocornmunication an annular space formed between the first and thirdcylinders and an annular space formed between the second and thirdcylinders.

2. A telescopic tube as claimed in claim 1, in which the external crosssectional area of the third cylinder is equal to the cross-sectionalarea of the annular space between the first and second cylinders.

3. A telescopic tube as claimed in claim 1 including a universal jointto which the first and second cylinders are connected at their endsremote from the base of the first cylinder.

4. A telescopic tube as claimed in claim 3, including a universal jointto which the third cylinder is connected at its end adjacent the base ofthe first cylinder.

References Cited UNITED STATES PATENTS 2,455,334 11/1948 Hill et al.137-580 M. CARY NELSON, Primary Examiner WILLIAM R. CLINE, AssistantExaminer U.S. C1. X.R.

